Antimitoscins: targeted inhibitors of mitochondrial biogenesis for eradicating cancer stem cells

ABSTRACT

Antibiotics having intrinsic anti-mitochondrial properties may be chemically modified to target the antibiotics to mitochondria, and the resulting “antimitoscins” may have enhanced anti-cancer properties, among other advantageous properties. Also described are methods for identifying antimitoscins, methods of using antimitoscins to target cancer stem cells, and pharmaceutical compositions for treating cancer containing one or more antimitoscins as the active ingredient. Specific antimitoscins compounds and groups of antimitoscins are also disclosed.

FIELD

The present disclosure relates to “antimitoscins,” antibiotics havingintrinsic anti-mitochondrial properties that are chemically modified totarget the antibiotics to mitochondria, and includes methods forsynthesizing antimitoscins, methods of using antimitoscins to targetcancer stem cells, and pharmaceutical compositions for both treatingcancer and reducing drug resistance in cancer cells, the pharmaceuticalcompositions containing one or more antimitoscins as the activeingredient.

BACKGROUND

Researchers have struggled to develop new anti-cancer treatments.Conventional cancer therapies (e.g. irradiation, alkylating agents suchas cyclophosphamide, and anti-metabolites such as 5-Fluorouracil) haveattempted to selectively detect and eradicate fast-growing cancer cellsby interfering with cellular mechanisms involved in cell growth and DNAreplication. Other cancer therapies have used immunotherapies thatselectively bind mutant tumor antigens on fast-growing cancer cells(e.g., monoclonal antibodies). Unfortunately, tumors often recurfollowing these therapies at the same or different site(s), indicatingthat not all cancer cells have been eradicated. Relapse may be due toinsufficient chemotherapeutic dosage and/or emergence of cancer clonesresistant to therapy. Hence, novel cancer treatment strategies areneeded.

Advances in mutational analysis have allowed in-depth study of thegenetic mutations that occur during cancer development. Despite havingknowledge of the genomic landscape, modern oncology has had difficultywith identifying primary driver mutations across cancer subtypes. Theharsh reality appears to be that each patient's tumor is unique, and asingle tumor may contain multiple divergent clone cells. What is needed,then, is a new approach that emphasizes commonalities between differentcancer types. Targeting the metabolic differences between tumor andnormal cells holds promise as a novel cancer treatment strategy. Ananalysis of transcriptional profiling data from human breast cancersamples revealed more than 95 elevated mRNA transcripts associated withmitochondrial biogenesis and/or mitochondrial translation. Sotgia etal., Cell Cycle, 11(23):4390-4401 (2012). Additionally, more than 35 ofthe 95 upregulated mRNAs encode mitochondrial ribosomal proteins (MRPs).Proteomic analysis of human breast cancer stem cells likewise revealedthe significant overexpression of several mitoribosomal proteins as wellas other proteins associated with mitochondrial biogenesis. Lamb et al.,Oncotarget, 5(22):11029-11037 (2014).

Functional inhibition of mitochondrial biogenesis using the off-targeteffects of certain bacteriostatic antibiotics or OXPHOS inhibitorsprovides additional evidence that functional mitochondria are requiredfor the propagation of cancer stem cells. The inventors recently showedthat a mitochondrial fluorescent dye (MitoTracker) could be effectivelyused for the enrichment and purification of cancer stem-like cells(CSCs) from a heterogeneous population of living cells. Farnie et al.,Oncotarget, 6:30272-30486 (2015). Cancer cells with the highestmitochondrial mass had the strongest functional ability to undergoanchorage-independent growth, a characteristic normally associated withmetastatic potential. The ‘Mito-high’ cell sub-population also had thehighest tumor-initiating activity in vivo, as shown using pre-clinicalmodels. The inventors also demonstrated that several classes ofnon-toxic antibiotics could be used to halt CSC propagation. Lamb etal., Oncotarget, 6:4569-4584 (2015). Because of the conservedevolutionary similarities between aerobic bacteria and mitochondria,certain classes of antibiotics or compounds having antibiotic activitycan inhibit mitochondrial protein translation as an off-targetside-effect.

SUMMARY

In view of the foregoing background, it is an object of this disclosureto demonstrate that existing antibiotics having intrinsicanti-mitochondrial properties can be chemically modified to target themitochondria and thus can be used to eradicate CSCs. Described hereinare examples of existing antibiotics having intrinsic anti-mitochondrialproperties that have been chemically modified with one or moremitochondria-targeting signals that, as a result, have enhancedanti-cancer properties. The term “antimitoscin” used herein broadlyrefers to an antibiotic having intrinsic anti-mitochondrial propertiesthat is chemically modified to target the antibiotic to mitochondria.The contemporary art considers intrinsic anti-mitochondrial activity inantibiotics to be an unwanted side-effect. Indeed, some potentialantibiotics have been excluded from trials due to excessiveanti-mitochondrial properties, and researchers have viewedanti-mitochondrial activity as a potential drawback. However, under thepresent approach, an antibiotic's intrinsic anti-mitochondrial activitycan become the basis for an entirely new therapeutic. The inventors havedetermined that these anti-mitochondrial properties may be harnessed andenhanced through chemical modification. As a result, antibiotics withintrinsic anti-mitochondrial activity may be re-purposed as noveltherapeutics for, among other potential therapies, anti-cancertreatments. These compounds may bind to either the large sub-unit or thesmall sub-unit of the mitochondrial ribosome (or in some instances,both) and inhibit mitochondrial biogenesis. Alternatively, thesecompounds may bind to the inner mitochondrial membrane to block theOXPHOS pathway and thus inhibit mitochondrial metabolism. The presentdisclosure further describes methods of synthesizing antimitoscins,methods of using antimitoscins to target cancer stem cells, andpharmaceutical compositions for both treating cancer and for reducingdrug resistance, the pharmaceutical compositions containing one or moreantimitoscins as the active ingredient. The present disclosure furtherdescribes methods for monitoring the effectiveness of an antimitoscintherapy. The methods may include obtaining a tissue sample from apatent, determining the level of at least one CSC marker in the sample,and classifying the antimitoscin therapy as effective if the sample isdetermined to have a decreased level of at least one CSC marker relativeto a threshold level. The CSC marker may be at least one of CD44, Sox2,Nanog, Oct 4, MYC, and ALDH.

The present disclosure may, in some embodiments, take the form of anantimitoscin. Exemplar antimitoscins are disclosed herein. In someembodiments, the antimitoscin comprises an antibiotic having intrinsicanti-mitochondrial properties and a mitochondria-targeting compound. Insome embodiments, the antibiotic is a member of the tetracycline family,the erthyromycin family, chloramphenicol, pyrvinium pamoate, atovaquone,and bedaquiline. The mitochondria-targeting compound may be a chemicalmodification to the antibiotic. In some embodiments, themitochondria-targeting compound is at least one compound selected fromthe group comprising a membrane targeting signal and a mitochondrialribosome-targeting signal. In some embodiments, the membrane targetingsignal is a compound selected from the group comprising palmitic acid,stearic acid, myristic acid, and oleic acid. In some embodiments, themitochondrial targeting signal is selected from the group comprisingtri-phenyl-phosphonium and guanidinium. In some embodiments, theantimitoscin possesses anti-cancer activity. In some embodiments, theantimitoscin binds to the large sub-unit or the small sub-unit of themitochondrial ribosome. In some embodiments, the antimitoscin binds toat least one of the large sub-units of the mitochondrial ribosome andthe small sub-unit of the mitochondrial ribosome. In some embodiments,the antimitoscin binds to the inner mitochondrial membrane. In someembodiments, an antimitoscin possesses radiosensitizing activity,photosensitizing activity, sensitizes cancer cells to chemotherapeuticagents, sensitizes cancer cells to natural substances, and/or sensitizescancer cells to caloric restriction. In some embodiments, the presentdisclosure relates to methods of treating cancer comprisingadministering to a patient in need thereof of a pharmaceuticallyeffective amount of an antimitoscin and a pharmaceutically acceptablecarrier. In some embodiments, the present disclosure relates to apharmaceutical composition for treating cancer containing, as the activeingredient, at least one antimitoscin. In some embodiments, thepharmaceutical composition comprises a plurality of antimitoscins.Embodiments of the present approach may take the form of methods ofsynthesizing antimitoscins. Embodiments of the present approach may alsotake the form of improving the anti-cancer properties of an antibiotic.

The inventors analyzed phenotypic properties of CSCs that could betargeted across a wide range of cancer types, and identified a strictdependence of CSCs on mitochondrial biogenesis for the clonal expansionand survival of a CSC. Previous work by the inventors demonstrated thatdifferent classes of FDA-approved antibiotics, and in particulartetracyclines such as doxycycline and erythromycin, have an off-targeteffect of inhibiting mitochondrial biogenesis. As a result, suchcompounds have efficacy for eradicating CSCs. However, these commonantibiotics were not designed to target the mitochondria, and thereforetheir anti-cancer efficacy is limited. Under the present approach,existing antibiotics having intrinsic anti-mitochondrial properties maybe chemically modified to form antimitoscins, to target themitochondria, and inhibit mitochondrial biogenesis and metabolism.Antimitoscins selectively inhibit CSCs because mitochondrial biogenesisis upregulated in CSCs and is required for propagation and survival. Asa result of their ability to inhibit mitochondrial biogenesis,antimitoscins have enhanced anti-cancer properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates members of the tetracycline family, including (A)tetracycline, (B) doxycycline, (C) tigecycline, and (D) minocycline.

FIG. 2 illustrates members of the erythromycin family, including (A)erythromycin, (B) clarithromycin, and (C) azithromycin.

FIG. 3 illustrates other antibiotics known to inhibit the mitochondrialribosome or mitochondrial protein translation via off-targetside-effects, including (A) chloramphenicol, (B) actinonin, and (C)levofloxacin.

FIG. 4 illustrates other antibiotics known to inhibit the mitochondrialribosome or mitochondrial protein translation via direct effects onmitochondrial oxygen consumption, including (A) pyrvinium pamoate, (B)atovaquone, and (C) bedaquiline.

FIG. 5 shows the structures of membrane-targeting signals including thefatty acids (A) stearic acid, (B) myristic acid, (C) palmitic acid, and(D) oleic acid.

FIG. 6 shows the structures of mitochondria-targeting signals including(A) tri-phenyl-phosphonium (TPP) and (B) guanidinium.

FIG. 7 shows a diagram of methods of converting antibiotics toantimitoscins by means of attachment (covalent or non-covalent) of amembrane or mitochondrial targeting signal to an antibiotic.

FIG. 8 shows the structures of two antimitoscins.

DESCRIPTION

The following description illustrates embodiments of the presentapproach in sufficient detail to enable practice of the presentapproach. Although the present approach is described with reference tothese specific embodiments, it should be appreciated that the presentapproach can be embodied in different forms, and this description shouldnot be construed as limiting any appended claims to the specificembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the present approach to those skilled in the art.

The mitochondria is an untapped gateway for treating a number ofafflictions, ranging from cancer to bacterial and fungal infections toaging. Functional mitochondria are required for the propagation ofcancer stem cells. Inhibiting mitochondrial biogenesis and metabolism incancer cells impedes the propagation of those cells. Mitochondrialinhibitors therefore represent a new class of anti-cancer therapeutics.

As disclosed herein, existing antibiotics having intrinsicanti-mitochondrial properties may be chemically-modified with at leastone mitochondria-targeting compound. The mitochondria-targeting compoundmay be a chemical modification to the antibiotic, and the chemicalmodification may be made according to chemical synthesis methods as areknown in the art. The mitochondria-targeting compound may be one of amembrane-targeting signal and a mitochondrial-ribosome targeting signal.In some embodiments, the antibiotic having intrinsic anti-mitochondrialproperties may be chemically-modified with at least onemembrane-targeting signal and at least one mitochondrial-targetingsignal. The resulting antimitoscin may be used as an anti-cancertherapeutic, as well as to target bacteria and pathogenic yeast, provideanti-aging benefits, function as radiosensitizers and/orphoto-sensitizers, and/or sensitize bulk cancer cells and cancer stemcells to chemotherapeutic agents, pharmaceuticals, and/or other naturalsubstances.

Novel antibiotics having intrinsic anti-mitochondrial properties thatare chemically modified to target the antibiotics to mitochondria,referred to herein as “antimitoscins,” may be formed by the addition ofat least one membrane-targeting signal and/or at least onemitochondrial-targeting signal to an antibiotic having intrinsicanti-mitochondrial properties. Such chemical modifications increase theefficiency of the specific targeting of these compounds to themitochondria and in particular the mitochondrial ribosome. The resultingcompound, an antimitoscin, has dramatically enhanced therapeuticproperties, including anti-cancer properties.

FIGS. 1-4 provide examples of known antibiotics having intrinsicanti-mitochondrial properties that are chemically modified to target theantibiotics to mitochondria to form an antimitoscin under the presentapproach. Antibiotics in the tetracycline family are examples ofantibiotics having intrinsic anti-mitochondrial properties that arechemically modified to target the antibiotics to mitochondria to formantimitoscins having efficacy as anti-cancer therapeutics. FIG. 1illustrates members of the tetracycline family, including (A)tetracycline, (B) doxycycline, (C) tigecycline, and (D) minocycline.Each of these broad-spectrum antibiotics may be chemically modified withat least one mitochondrial ribosome-targeting compound to form anantimitoscin. It should be appreciated that the specific antibioticsshown are demonstrative, and that the scope of the present approach isnot limited to only those structures shown. For example, other membersof the tetracycline family not specifically identified herein may beused as an initial compound for forming an antimitoscin. This mayinclude, as a non-exhaustive list of examples only, chlortetracycline,oxytetracycline, demeclocycline, lymecycline, meclocycline,methacycline, rolitetracycline, chlortetracycline, omadacycline, andsarecycline.

Antibiotics in the erythromycin family are additional examples ofantibiotics having intrinsic anti-mitochondrial properties that arechemically modified to target the antibiotics to mitochondria to formantimitoscins having efficacy as anti-cancer therapeutics. FIG. 2 showsthe chemical structures for sample erythromycin family members,including (A) erythromycin, (B) azithromycin, and (C) clarithromycin.Each of these antibiotics may be chemically modified with at least onemitochondria-targeting compound to form an antimitoscin. It should beappreciated that the specific antibiotics shown are demonstrative, andthat the scope of the present approach is not limited to only thosestructures shown. For example, other members of the tetracycline familynot specifically identified herein may be used as an initial compoundfor forming an antimitoscin. This may include, for example,chlortetracycline, oxytetracycline, demeclocycline, lymecycline,meclocycline, methacycline, minocycline, rolitetracycline, tigecycline,omadacycline, and sarecycline, to name a few further examples.

Other known antibiotics having intrinsic anti-mitochondrial propertiesthat are chemically modified to target the antibiotics to mitochondriamay be antimitoscins. FIG. 3 shows other antibiotics known to inhibitthe mitochondrial ribosome or mitochondrial protein translation as anoff-target side-effect. These examples include chloramphenicol,actinonin, and levofloxacin. Each of these compounds may bechemically-modified with at least one mitochondria-targeting compound toform an antimitoscin. FIG. 4 shows other antibiotics known to impactmitochondrial oxygen consumption by interfering with mitochondrialcomplexes I, II, III, IV, and/or V. These examples include pyrviniumpamoate, atovaquone, and bedaquiline. Each of these compounds may bechemically-modified with at least one mitochondria-targeting compound toform an antimitoscin.

Unlike antibiotics, antimitoscins are specifically designed to targetmitochondria by attachment of at least one membrane-targeting signaland/or at least one mitochondrial-targeting signal. FIG. 5 providesexamples of membrane-targeting signals, including fatty acids such aspalmitate, stearate, myristate, and oleate. It should be appreciatedthat this is not a comprehensive list of membrane-targeting signals, andthat an unlisted membrane-targeting signal may be used without departingfrom the present approach. FIG. 6 provides examples ofmitochondria-targeting signals, including tri-phenyl-phosphonium (TPP)and guanidinium-based moieties. It should be appreciated that this isnot a comprehensive list of mitochondria-targeting signals, and that anunlisted mitochondria-targeting signal may be used without departingfrom the present approach.

FIG. 7 shows a diagram of methods of converting antibiotics toantimitoscins by means of attachment (covalent or non-covalent) of amembrane or mitochondrial targeting signal 701 to one or more ofantibiotics 703, nutraceuticals 705, conventional chemotherapies 707 asare known in the art, and other compounds or therapies 709.

As described herein, an antimitoscin may be formed bychemically-modifying an antibiotic having intrinsic anti-mitochondrialproperties with at least one membrane-targeting signal and/or at leastone mitochondria-targeting signal. FIG. 8 shows two examples ofantimitoscins. In these examples, the side chain of a tetracyclinefamily member has been replaced with (A) palmitic acid and (B) acarbon-spacer-arm and TPP. It should be appreciated that themitochondria-targeting compound(s) may be linked to the antibiotic inother locations without departing from the present approach.

The specific antimitoscin formulas shown in FIG. 8 are examples ofantimitoscins formed from the exemplar antibiotics identified in FIGS.1-4. It should be appreciated that an antimitoscin may be selected fortherapeutic use individually, or in combination with one or moreantimitoscin, and/or with other substances to enhance the efficacy ofother therapeutics. For example, antimitoscins formed from differentantibiotics may be used together in a therapeutic formulation. Further,antimitoscins formed from the antibiotic but having differentmitochondria-targeting compounds (such as the structures shown in FIG.8) may be used together in a therapeutic formulation. The therapeuticsmay be used in the form of usual pharmaceutical compositions which maybe prepared using one or more known methods. For example, apharmaceutical composition may be prepared by using diluents orexcipients such as, for example, one or more fillers, bulking agents,binders, wetting agents, disintegrating agents, surface active agents,lubricants, and the like as are known in the art. Various types ofadministration unit forms can be selected depending on the therapeuticpurpose(s). Examples of forms for pharmaceutical compositions include,but are not limited to, tablets, pills, powders, liquids, suspensions,emulsions, granules, capsules, suppositories, injection preparations(solutions and suspensions), topical creams, and other forms as may beknown in the art. For the purpose of shaping a pharmaceuticalcomposition in the form of tablets, any excipients which are known maybe used, for example carriers such as lactose, white sugar, sodiumchloride, glucose, urea, starch, calcium carbonate, kaolin,cyclodextrins, crystalline cellulose, silicic acid and the like; binderssuch as water, ethanol, propanol, simple syrup, glucose solutions,starch solutions, gelatin solutions, carboxymethyl cellulose, shelac,methyl cellulose, potassium phosphate, polyvinylpyrrolidone, etc.Additionally, disintegrating agents such as dried starch, sodiumalginate, agar powder, laminalia powder, sodium hydrogen carbonate,calcium carbonate, fatty acid esters of polyoxyethylene sorbitan, sodiumlaurylsulfate, monoglyceride of stearic acid, starch, lactose, etc., maybe used. Disintegration inhibitors such as white sugar, stearin, coconutbutter, hydrogenated oils; absorption accelerators such as quaternaryammonium base, sodium laurylsulfate, etc., may be used. Wetting agentssuch as glycerin, starch, and others known in the art may be used.Adsorbing agents such as, for example, starch, lactose, kaolin,bentonite, colloidal silicic acid, etc., may be used. Lubricants such aspurified talc, stearates, boric acid powder, polyethylene glycol, etc.,may be used. If tablets are desired, they can be further coated with theusual coating materials to make the tablets as sugar coated tablets,gelatin film coated tablets, tablets coated with enteric coatings,tablets coated with films, double layered tablets, and multi-layeredtablets. Pharmaceutical compositions adapted for topical administrationmay be formulated as ointments, creams, suspensions, lotions, powders,solutions, pastes, gels, foams, sprays, aerosols, or oils. Suchpharmaceutical compositions may include conventional additives whichinclude, but are not limited to, preservatives, solvents to assist drugpenetration, co-solvents, emollients, propellants, viscosity modifyingagents (gelling agents), surfactants, and carriers.

Antimitoscins may also be used to reverse drug resistance in cancercells. Drug resistance is thought to be based, at least in part, onincreased mitochondrial function in cancer cells. In particular, cancercells demonstrating resistance to endocrine therapies, such astamoxifen, are expected to have increased mitochondrial function.Antimitoscins inhibit mitochondrial function, and therefore are usefulin reducing and, in some cases reversing, drug resistance in cancercells. Additionally, previously generated data suggests that inhibitorsof mitochondrial function that target the mitochondrial ribosome,referred to as “mitoriboscins,” may be used to target bacteria andpathogenic yeast, provide anti-aging benefits, function asradiosensitizers and/or photo-sensitizers, sensitize bulk cancer cellsand cancer stem cells to chemotherapeutic agents, pharmaceuticals,and/or other natural substances, such as dietary supplements and caloricrestriction. Given their mitochondrial-inhibition properties,antimitoscins may similarly be used to target bacteria and pathogenicyeast, provide anti-aging benefits, function as radiosensitizers and/orphoto-sensitizers, sensitize bulk cancer cells and cancer stem cells tochemotherapeutic agents, pharmaceuticals, and/or other naturalsubstances.

In addition to antibiotics, other compounds having antibiotic activitymay be modified with a membrane or mitochondria-targeting signal to haveenhanced anti-cancer activity. For example, nutraceuticals andconventional chemotherapies may be modified with at least onemitochondria-targeting compound(s) to specifically target themitochondria. The efficacy of such compounds may be increased whenspecifically targeting the mitochondria. Examples of nutraceuticalshaving antibiotic activity that may be modified to target themitochondria include caffeic acid phenethyl ester (found in beepropolis), ascorbic acid (vitamin C) and other vitamins and traceminerals, polyphenols, epigallocatechin-3-gallate, resveratrol, andquercetin. It should be appreciated that this is not a comprehensivelist of nutraceuticals having antibiotic activity, and that an unlistednutraceutical may be used without departing from the present approach.

The table below summarizes demonstrative antibiotics and chemicaltargeting signals that may be linked to create an antimitoscin.

TABLE 1 Demonstrative constituents for creating an antimitoscin.FDA-Approved Antibiotics Tetracycline Family tetracycline minocyclinedoxycycline tigecycline among others Erythromycin Family erythromycinclarithromycin azithromycin among others Other(s) & OXPHOSchloramphenicol pyrvinium pamoate atovaquone Bedaquiline among othersChemical Modifications Membrane-Targeting-Signals palmitic acid stearicacid myristic acid oleic acid among othersMitochondrial-Targeting-Signals tri-phenyl-phosphonium (TPP)guanidinium-related groups choline esters among others OtherApplications Nutraceuticals Conventional chemotherapies Newly DiscoveredCompounds Specific Formulations Inert ingredients Cyclodextrins alphabeta Gamma Combination Therapies

The present disclosure also relates to methods of monitoring theeffectiveness of antimitoscin therapies. In some embodiments, one ormore CSC markers may be monitored to determine the effectiveness oftreatment with one or more antimitoscins. Relative levels of CSC markersmay decrease in response to antimitoscin treatment, as compared to anuntreated control. In some embodiments, the CSC marker is at least oneof CD44, Sox2, Nanog, Oct4, MYC, and ALDH. The relative levels of one ormore CSC markers may be measured in a tumor tissue sample. The relativelevels of one or more CSC markers may be measured by any number of waysknown in the art for measuring RNA, DNA, and/or protein levels of amarker including, without limitation, quantitative PCR and/or RT-PCRkits, microarrays, Northern blots, and Western blots.

The terminology used in the description of the invention herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe invention and the appended claims, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The invention includes numerousalternatives, modifications, and equivalents as will become apparentfrom consideration of the following detailed description.

It will be understood that although the terms “first,” “second,”“third,” “a),” “b),” and “c),” etc. may be used herein to describevarious elements of the invention should not be limited by these terms.These terms are only used to distinguish one element of the inventionfrom another. Thus, a first element discussed below could be termed anelement aspect, and similarly, a third without departing from theteachings of the present invention. Thus, the terms “first,” “second,”“third,” “a),” “b),” and “c),” etc. are not intended to necessarilyconvey a sequence or other hierarchy to the associated elements but areused for identification purposes only. The sequence of operations (orsteps) is not limited to the order presented in the claims.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the present applicationand relevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. The terminology used inthe description of the invention herein is for the purpose of describingparticular embodiments only and is not intended to be limiting of theinvention. All publications, patent applications, patents and otherreferences mentioned herein are incorporated by reference in theirentirety. In case of a conflict in terminology, the presentspecification is controlling.

Also, as used herein, “and/or” refers to and encompasses any and allpossible combinations of one or more of the associated listed items, aswell as the lack of combinations when interpreted in the alternative(“or”).

Unless the context indicates otherwise, it is specifically intended thatthe various features of the invention described herein can be used inany combination. Moreover, the present invention also contemplates thatin some embodiments of the invention, any feature or combination offeatures set forth herein can be excluded or omitted. To illustrate, ifthe specification states that a complex comprises components A, B and C,it is specifically intended that any of A, B or C, or a combinationthereof, can be omitted and disclaimed.

As used herein, the transitional phrase “consisting essentially of” (andgrammatical variants) is to be interpreted as encompassing the recitedmaterials or steps “and those that do not materially affect the basicand novel characteristic(s)” of the claimed invention. Thus, the term“consisting essentially of” as used herein should not be interpreted asequivalent to “comprising.”

The term “about,” as used herein when referring to a measurable value,such as, for example, an amount or concentration and the like, is meantto encompass variations of ±20%, ±10%, ±5%, ±1%, ±0.5%, or even ±0.1% ofthe specified amount. A range provided herein for a measurable value mayinclude any other range and/or individual value therein.

Having thus described certain embodiments of the present invention, itis to be understood that the invention defined by the appended claims isnot to be limited by particular details set forth in the abovedescription as many apparent variations thereof are possible withoutdeparting from the spirit or scope thereof as hereinafter claimed.

What is claimed is:
 1. An antimitoscin.
 2. The antimitoscin of claim 1,wherein the antimitoscin comprises an antibiotic having intrinsicanti-mitochondrial properties and a mitochondria-targeting compound. 3.The antimitoscin of claim 2, wherein the antibiotic is selected from thegroup comprising at least one member of the tetracycline family, atleast one member of the erthyromycin family, chloramphenicol, pyrviniumpamoate, atovaquone, and bedaquiline.
 4. The antimitoscin of claim 2,wherein the mitochondria-targeting compound is at least one compoundselected from the group comprising a membrane targeting signal and amitochondrial ribosome-targeting signal.
 5. The antimitoscin of claim 4,wherein the membrane targeting signal is a compound selected from thegroup comprising palmitic acid, stearic acid, myristic acid, and oleicacid.
 6. The antimitoscin of claim 4, wherein the mitochondrialtargeting signal is a compound selected from the group comprisingtri-phenyl-phosphonium and guanidinium.
 7. The antimitoscin of claim 1,wherein the antimitoscin possesses anti-cancer activity.
 8. Theantimitoscin of claim 1, wherein the antimitoscin binds to the largesub-unit of the mitochondrial ribosome.
 9. The antimitoscin of claim 1,wherein the antimitoscin binds to the small sub-unit of themitochondrial ribosome.
 10. The antimitoscin of claim 1, wherein theantimitoscin binds to at least one of the large sub-unit of themitochondrial ribosome or the small sub-unit of the mitochondrialribosome.
 11. The antimitoscin of claim 1, wherein the antimitoscinbinds to a mitochondrial membrane.
 12. The antimitoscin of claim 1,wherein the antimitoscin possesses radiosensitizing activity.
 13. Theantimitoscin of claim 1, wherein the antimitoscin possessesphotosensitizing activity.
 14. The antimitoscin of claim 1, wherein theantimitoscin sensitizes cancer cells to chemotherapeutic agents.
 15. Theantimitoscin of claim 1, wherein the antimitoscin sensitizes cancercells to natural substances.
 16. The antimitoscin of claim 1, whereinthe antimitoscin sensitizes cancer cells to caloric restriction.
 17. Amethod of treating cancer comprising administering to a patient in needthereof of a pharmaceutically effective amount of an antimitoscin and apharmaceutically acceptable carrier.
 18. A pharmaceutical compositionfor treating cancer containing, as the active ingredient, at least oneantimitoscin.
 19. The pharmaceutical composition of claim 18, comprisinga plurality of antimitoscins.
 20. An antimitoscin synthesis methodcomprising: chemically modifying an antibiotic having anti-cancerproperties with a mitochondria-targeting compound.
 21. The method ofclaim 20, wherein the antibiotic is selected from the group comprisingat least one member of the tetracycline family, at least one member ofthe erthyromycin family, chloramphenicol, pyrvinium pamoate, atovaquone,and bedaquiline.
 22. The method of claim 20, wherein themitochondria-targeting compound is at least one compound selected fromthe group comprising a membrane targeting signal and a mitochondrialribosome-targeting signal.
 23. The method of claim 22, wherein themembrane targeting signal is at least one compound selected from thegroup comprising palmitic acid, stearic acid, myristic acid, and oleicacid.
 24. The method of claim 22, wherein the mitochondrial targetingsignal is at least one compound selected from the group comprisingtri-phenyl-phosphonium and guanidinium.
 25. A method for improving theanti-cancer properties of an antibiotic, the method comprising:chemically modifying an antibiotic having anti-cancer properties with amitochondria-targeting compound.
 26. The method of claim 25, wherein theantibiotic is selected from the group comprising at least one member ofthe tetracycline family, at least one member of the erthyromycin family,chloramphenicol, pyrvinium pamoate, atovaquone, and bedaquiline.
 27. Themethod of claim 25, wherein the mitochondria-targeting compound is atleast one compound selected from the group comprising a membranetargeting signal and a mitochondrial ribosome-targeting signal.
 28. Themethod of claim 27, wherein the membrane targeting signal is at leastone compound selected from the group comprising palmitic acid, stearicacid, myristic acid, and oleic acid.
 29. The method of claim 27, whereinthe mitochondrial targeting signal is at least one compound selectedfrom the group comprising tri-phenyl-phosphonium and guanidinium.
 30. Amethod for monitoring the effectiveness of an antimitoscin therapy, themethod comprising: obtaining a tissue sample from a patent; determiningthe level of at least one CSC marker in the sample; and classifying theantimitoscin therapy as effective if the sample is determined to have adecreased level of at least one CSC marker relative to a thresholdlevel.
 31. The method of claim 30, wherein the CSC marker is at leastone of CD44, Sox2, Nanog, Oct 4, MYC, and ALDH.